ALSA: pci: Constify snd_ac97_bus_ops definitions

Now snd_ac97_bus() takes the const ops pointer, so we can define the
snd_ac97_bus_ops locally as const as well for further optimization.

There should be no functional changes by this patch.

Link: https://lore.kernel.org/r/20200103081714.9560-28-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/intel8x0.c

@@ -2138,12 +2138,12 @@ static int snd_intel8x0_mixer(struct intel8x0 *chip, int ac97_clock,
 	int err;
 	unsigned int i, codecs;
 	unsigned int glob_sta = 0;
-	struct snd_ac97_bus_ops *ops;
-	static struct snd_ac97_bus_ops standard_bus_ops = {
+	const struct snd_ac97_bus_ops *ops;
+	static const struct snd_ac97_bus_ops standard_bus_ops = {
 		.write = snd_intel8x0_codec_write,
 		.read = snd_intel8x0_codec_read,
 	};
-	static struct snd_ac97_bus_ops ali_bus_ops = {
+	static const struct snd_ac97_bus_ops ali_bus_ops = {
 		.write = snd_intel8x0_ali_codec_write,
 		.read = snd_intel8x0_ali_codec_read,
 	};